Disk drive suspension

ABSTRACT

In a disk drive suspension including a baseplate and a load beam, a boss portion and protrusions are formed on the baseplate. The protrusions are formed in positions on a first surface of the baseplate off a reference mounting surface in contact with a suspension bearing surface of an actuator arm. Further, the protrusions are formed on a second surface located opposite from the first surface and project relative to the thickness of the baseplate. These protrusions serve to prevent a plurality of baseplates from closely contacting one another during their manufacture.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.12/757,204, filed Apr. 9, 2010, which is based upon and claims thebenefit of priority from prior Japanese Patent Application No.2009-099111, filed Apr. 15, 2009, the entire contents of both of whichare incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a baseplate of a disk drive suspension,and more particularly, to a baseplate free from sticking duringmanufacture.

2. Description of the Related Art

A hard disk drive (HDD) is used in an information processing device suchas a personal computer. The HDD comprises a magnetic disk rotatableabout a spindle, a carriage arm (actuator arm) turnable about a pivot,etc. A disk drive suspension (hereinafter simply referred to as a“suspension”) is disposed on the distal end portion of the actuator arm.

The suspension comprises a baseplate, load beam, flexure, etc. Thebaseplate is fixed to the actuator arm. The load beam is mounted on thebaseplate. The flexure is located along the load beam. A slider ismounted on a tongue portion formed on the flexure. A transducer isdisposed on the slider. The transducer is an element for reading orwriting.

As described in Jpn. Pat. Appln. KOKAI Publications Nos. 2007-287296,2008-004142, and 7-192420, the baseplate of the suspension is fixed to asuspension bearing surface of the actuator arm. For example, a bossportion formed on the baseplate is inserted into a hole in the actuatorarm. The baseplate is fixed to the actuator arm in such a manner thatthe boss portion is pressed by a jig from the inside and expanded byplastic deformation.

As one such method in which the baseplate is fixed to the actuator armby expanding the boss portion as described above, there is a diameterexpanding process such as ball caulking disclosed in Jpn. Pat. Appin.KOKAI Publication No. 7-192420. In this diameter expanding process, theboss portion of the baseplate is fitted into the hole in the actuatorarm. A steel ball for use as a caulking jig is press-fitted into thehole in the boss portion through one opening and discharged through theother opening. Thereupon, the diameter of the boss portion is expanded.The expanded boss portion is tightly fitted to the inner surface of thehole in the actuator arm. Consequently, the baseplate is fixed to theactuator arm.

The baseplate is fabricated by press forming. Since the baseplate iswork-hardened, the boss portion is unduly hard. Accordingly, thebaseplate is adjusted to a hardness suitable for the diameter expandingprocess by a heat treatment.

The heat treatment is simultaneously performed for a plurality ofbaseplates. In this heat treatment, a large number of baseplates arecollectively charged at random into a heating furnace. In some cases,therefore, the baseplates may be heated with their flat surfacesaccidentally overlapping one another. If the flat surfaces are incontact with one another as the baseplates are heat-treated, surfacesubstances of the baseplates may sometimes be stuck to one another by,for example, diffusion bonding.

In some cases, moreover, the baseplates may be surface-treated in orderto remove solid particulate dust from the surfaces of the baseplates ormake the surfaces suitable for the ball caulking. If the flat surfacesof the surface-treated baseplates contact one another, the baseplatesmay be stuck to one another by a surface tension or the like.

If the baseplates stuck in this manner are forced to be separated, theyare inevitably deformed and become unusable. Thus, if the baseplatesstick to one another, the yield rate of production is reduced.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a disk drive suspension configured sothat a plurality of baseplates can be prevented from sticking to oneanother in baseplate manufacturing processes or the like.

The invention is a disk drive suspension which comprises a baseplatefixed to a suspension bearing surface of an actuator arm of a disk driveand a load beam mounted on the baseplate. The baseplate comprises afirst surface including a reference mounting surface in contact with thesuspension bearing surface of the actuator arm, a second surface locatedopposite from the first surface, a boss portion configured to beinserted into a mounting hole formed in the actuator arm, and aprotrusion formed so as to project outwardly relative to the thicknessof the baseplate from at least one of the second surface and a part ofthe first surface off the reference mounting surface.

In an aspect of the invention, the protrusion is formed on each of thefirst and second surfaces of the baseplate. A hole into which theprotrusion is inserted may be formed in that region of the load beamwhich overlaps the baseplate. Further, the protrusion may be shaped soas to project in a circular arc from the first or second surface along aprofile relative to the thickness of the baseplate. In another aspect ofthe invention, the protrusion is formed of a rough surface comprising alarge number of minute irregularities on the baseplate.

According to the present invention, a plurality of baseplates can beprevented from sticking to one another even when they are handled atrandom in baseplate manufacturing processes or the like. Thus, the yieldrate of baseplate production can be improved.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 is a perspective view showing an example of a disk drive;

FIG. 2 is a partial sectional view of the disk drive shown in FIG. 1;

FIG. 3 is a perspective view of a suspension according to a firstembodiment of the invention;

FIG. 4 is a plan view of the suspension taken from the side oppositefrom FIG. 3;

FIG. 5 is a plan view of a baseplate of the suspension shown in FIG. 3;

FIG. 6 is a sectional view showing a part of an actuator arm and aprofile of the baseplate taken along line F6-F6 of FIG. 5;

FIG. 7 is a perspective view showing how the baseplate shown in FIG. 3is laid on another baseplate;

FIG. 8 is a sectional view of a baseplate according to a secondembodiment of the invention;

FIG. 9 is a plan view of a baseplate according to a third embodiment ofthe invention;

FIG. 10 is a side view of the baseplate shown in FIG. 9;

FIG. 11 is a plan view of a baseplate according to a fourth embodimentof the invention; and

FIG. 12 is a sectional view of the baseplate taken along line F12-F12 ofFIG. 11.

DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of the present invention will now be described withreference to FIGS. 1 to 7.

A hard disk drive (HDD) 1 shown in FIG. 1 comprises a case 2, disks 4,carriage 6, positioning motor 7, etc. The disks 4 are rotatable about aspindle 3. The carriage 6 is turnable about a pivot 5. The positioningmotor 7 drives the carriage 6. The case 2 is sealed by a lid (notshown).

FIG. 2 is a sectional view typically showing a part of the disk drive 1.As shown in FIG. 2, the carriage 6 is provided with a plurality ofactuator arms 8. A disk drive suspension (hereinafter simply referred toas a “suspension”) 10 is mounted on a suspension bearing surface 9 (FIG.6) formed on each actuator arm 8.

A slider 11 that constitutes a magnetic head is disposed on the distalend of each suspension 10. If the disks 4 rotate at high speed about thespindle 3, an air bearing is formed between each disk 4 and slider 11.If the actuator arms 8 are turned by the positioning motor 7, thesuspensions 10 move diametrically relative to the disks 4. Thereupon,each slider 11 moves to a desired track of the disk 4. Each slider 11,which functions as the magnetic head, comprises a reading element andwriting element (not shown).

FIG. 3 shows an example of the suspension 10. FIG. 4 is a plan view ofthe suspension 10 taken from the side opposite from FIG. 3. Thesuspension 10 comprises a base portion 21 including a baseplate 20, loadbeam 22, flexure 23 with conductors, etc. FIG. 5 shows an example of thebaseplate 20. The baseplate 20 will be described in detail later.

As shown in FIGS. 3 and 4, the load beam 22 comprises a proximal portion22 a and distal end portion 22 b. The proximal portion 22 a of the loadbeam 22 is laid on the baseplate 20. The proximal portion 22 a is fixedto the baseplate 20 by fixing means, such as laser welding. The loadbeam 22 is about 30 to 100 μm thick, for example. A pair of springyhinge portions 30 are formed on a part of the load beam 22.

The hinge portions 30 are formed near the baseplate 20 and can bendrelative to its thickness. Instead of forming the hinge portions 30 onthe load beam 22, a hinge member thinner than the baseplate 20 may bedisposed between the baseplate 20 and load beam 22.

The flexure 23 is laid on the load beam 22 relative to its thickness soas to extend along the load beam 22. A tongue portion (gimbal portion)24 is disposed near the distal end of the flexure 23. As shown in FIG.3, the slider 11 is mounted on the tongue portion 24.

The baseplate 20 is formed of austenite stainless steel, such as SUS304or SUS305. The baseplate 20 is fabricated by press forming. Further, thehardness and surface condition of the baseplate 20 are adjusted by aheat treatment. The baseplate 20 is thicker than the load beam 22 andis, for example, 100 μm thick or more.

The baseplate 20 comprises a plate portion 50 and boss portion 51. Theplate portion 50 of the baseplate 20 has a first surface 20 a and secondsurface 20 b. As shown in FIG. 6, the first surface 20 a faces thesuspension bearing surface 9 of the actuator arm 8. The second surface20 b is located opposite from the first surface 20 a. The first andsecond surfaces 20 a and 20 b are flat. The boss portion 51 ispress-formed into a short cylindrical shape. The boss portion 51projects outwardly from the first surface 20 a relative to the thicknessof the baseplate 20.

The first surface 20 a comprises a flat reference mounting surface S.The reference mounting surface S is formed on the side of the bossportion 51 with respect to a two-dot chain line L shown in FIG. 3. Themounting surface S contacts the suspension bearing surface 9 when thebaseplate 20 is fixed to the actuator arm 8.

A first protrusion 61 is formed in a region of the first surface 20 a ofthe baseplate 20 off the reference mounting surface S. The firstprotrusion 61 is formed so as to project outwardly relative to thethickness of the baseplate 20 from the first surface 20 a. Secondprotrusions 62 are formed on the second surface 20 b. The secondprotrusions 62 are formed so as to project outwardly relative to thethickness of the baseplate 20 from the second surface 20 b. The firstand second protrusions 61 and 62 are examples of protrusions accordingto the present invention.

The first and second protrusions 61 and 62 are formed near peripheraledges of the plate portion 50. As shown in FIGS. 5 and 6, for example,each of the protrusions 61 and 62 is in the shape of a column taperedtoward its distal end. The protrusions 61 and 62 are not limited to thisshape and may alternatively be, for example, columnar, prismatic,conical, pyramidal, or hemispherical.

The first and second protrusions 61 and 62 are formed on at least one ofthe first and second surfaces 20 a and 20 b so as to be at least one innumber. The protrusions 61 and 62 are formed by, for example, coiningthe baseplate 20. Coining is a kind of plastic working performed byusing press equipment.

In the coining work, the baseplate 20 is struck relative to itsthickness by a die set having a precise forming surface, whereby plasticflow is caused in the baseplate 20. Thereupon, the plate portion 50having the first and second smooth surfaces 20 a and 20 b, boss portion51, first and second protrusions 61 and 62, etc., can be formed. By thecoining, occurrence of contamination, which may be caused by machiningsuch as cutting, can be avoided. The contamination is particulate dustthat forms foreign matter. Recesses are press-formed on the backside ofthe first and second protrusions 61 and 62.

The first protrusion 61 is formed on a part of the first surface 20 aoff the reference mounting surface S. Specifically, the first protrusion61 is located so as not to interfere with the actuator arm 8 when thebaseplate 20 is fixed to the suspension bearing surface 9 of the arm 8.Thus, the baseplate 20 can be smoothly mounted on the actuator arm 8despite the presence of the first protrusion 61. Further, the firstprotrusion 61 does not need to be disposed on the reference mountingsurface S that requires high shape accuracy. Consequently, the mountingaccuracy of the baseplate 20 on the suspension bearing surface 9 can beprevented from becoming lower.

As shown in FIG. 4, holes 70 are formed in the load beam 22,corresponding in position to the second protrusions 62. The secondprotrusions 62 are inserted individually into the holes 70 with the loadbeam 22 laid on the baseplate 20. Instead of providing the load beam 22with the holes 70, the load beam 22 may be formed with recesses intowhich the second protrusions 62 can be inserted.

As shown in FIG. 4, the flexure 23 is also formed with a hole 71, whichenables it to avoid interfering with its corresponding second protrusion62. The second protrusion 62 concerned is inserted into the hole 71 withthe flexure 23 laid on the load beam 22. Instead of providing theflexure 23 with the hole 71, the flexure 23 may be formed with a recessinto which the second protrusion 62 can be inserted.

As shown in FIG. 6, each actuator arm 8 of the carriage 6 is providedwith the suspension bearing surface 9. The baseplate 20 is fixed to thebearing surface 9. The bearing surface 9 is precisely finished by, forexample, polishing so as to be flat. A circular mounting hole 8 a isformed in a region of the actuator arm 8 including the suspensionbearing surface 9.

Before the baseplate 20 is fixed to the suspension bearing surface 9 ofthe actuator arm 8, the outside diameter of the boss portion 51 isslightly smaller than the inside diameter of the mounting hole 8 a ofthe actuator arm 8.

The boss portion 51 is inserted into the mounting hole 8 a of theactuator arm 8. The boss portion 51 is pressed from the inside andplastically deformed so that its diameter increases. Thereupon, theouter peripheral surface of the boss portion 51 is fixed to the innerperipheral surface of the mounting hole 8 a.

The following is a description of the effect of the baseplate 20constructed in this manner.

After a plurality of baseplates 20 are fabricated by press forming, theyare subjected to processes for deburring, washing, etc., if necessary,and then heat-treated. In this heat treatment, the baseplates 20 arecharged at random into a heating furnace and heated simultaneously. Insome cases, therefore, the baseplates 20 may be superposed on oneanother as they are heated.

As shown in FIG. 7, for example, two of the baseplates 20 may besuperposed as they are heat-treated. In this case, the baseplates 20contact each other through some of the second protrusions 62, forexample, so that a gap is formed between the baseplates 20. Thus, thesecond surface 20 b of one baseplate 20 can avoid closely contactingthat of the other baseplate 20.

Specifically, the superposed baseplates 20, each comprising the firstand second protrusions 61 and 62, only partially contact each other.Thus, the baseplates 20 can avoid being stuck to each other by the heattreatment. If the baseplates 20 stick to each other through the firstprotrusion 61 or second protrusions 62, they can be easily separatedfrom each other. As the baseplates 20 are separated, therefore, they canbe prevented from being deformed, so that their yield rate of productioncan be improved.

Although the effect of preventing the baseplates 20 from sticking toeach other during the heat treatment has been described above, thepresent invention is not limited to the prevention of sticking duringthe heat treatment. For example, the invention is also applicable to theprevention of sticking of the baseplates 20 during a surface treatmentor sticking attributable to a surface tension.

A second embodiment of the present invention will now be described withreference to FIG. 8.

FIG. 8 shows a baseplate 20A according to the second embodiment. Thebaseplate 20A comprises first and second protrusions 81 and 82 on firstand second surfaces 20 a and 20 b, respectively. The first and secondprotrusions 81 and 82 are examples of protrusions according to thepresent invention. The protrusions 81 and 82 differ from the first andsecond protrusions 61 and 62 of the first embodiment in shape.

The first and second protrusions 81 and 82 of the baseplate 20A aredomed. The protrusions 81 and 82 project in a circular arc from thefirst or second surface 20 a or 20 b along a profile relative to thethickness of the baseplate 20A.

Since configurations and functions other than those described above arecommon to the baseplates of the first and second embodiments, likenumbers are used to designate common portions of these two embodiments,and a description of those portions is omitted.

According to the baseplate 20A constructed in this manner, the first andsecond protrusions 81 and 82 are domed. If a plurality of baseplates 20Aare superposed on one another as they are heat-treated, therefore, thesuperposed baseplates are brought substantially into point contact withone another. Specifically, the areas of contact between the superposedbaseplates 20A are very limited, compared to the case of surface contactbetween the plate portions 50. Thus, the baseplates 20A can be preventedmore effectively from sticking to one another due to the heat treatment.

A third embodiment of the present invention will now be described withreference to FIGS. 9 and 10.

A baseplate 20B according to the third embodiment shown in FIGS. 9 and10 comprises first and second protrusions 91 and 92 on first and secondsurfaces 20 a and 20 b, respectively. The first and second protrusions91 and 92 are examples of protrusions according to the presentinvention.

The first and second protrusions 91 and 92 are riblike. The firstprotrusions 91 are located off a reference mounting surface S on thefirst surface 20 a. In other words, the first protrusions 91 are locatedso as to be kept apart from an actuator arm 8. Each first protrusion 91extends in a continuous straight line transversely relative to the plateportion 50. Each second projection 92 extends in a continuous straightline transversely relative to the plate portion 50 on the second surface20 b.

The first and second protrusions 91 and 92 are formed by press-formingthe plate portion 50. The protrusions 91 and 92 project outwardly in acircular arc relative to the thickness of the baseplate 20B from thefirst and second surfaces 20 a and 20 b, respectively.

Each of the first and second protrusions 91 and 92 is not limited to theshape of the straight line, when viewed vertically from above or below,and may alternatively be in a continuous line curved or bent at aplurality of points. The direction in which each of the protrusions 91and 92 continuously extends is not limited to the transverse directionof the plate portion 50. Further, second protrusions 62 similar to thoseof the first embodiment may be formed on the second surface 20 b of thebaseplate 20B.

Since configurations and functions other than those described above arecommon to the baseplates of the first and third embodiments, likenumbers are used to designate common portions of these two embodiments,and a description of those portions is omitted.

A fourth embodiment of the present invention will now be described withreference to FIGS. 11 and 12.

In a baseplate 20C according to the fourth embodiment shown in FIGS. 11and 12, rough surfaces 95 and 96 are formed on first and second surfaces20 a and 20 b, respectively, of a plate portion 50. The rough surfaces95 and 96 are formed of a large number of minute press-formedirregularities. The rough surfaces 95 and 96 are formed by a surfacetreatment called texturing. These rough surfaces 95 and 96 constituteprotrusions according to the present invention.

The rough surfaces 95 and 96 may be provided partially or substantiallyentirely covering the first and second surfaces 20 a and 20 b.

Flat portions 97 for welding are formed individually on those parts ofthe second surface 20 b to which the load beam 22 is fixed by laser spotwelding or the like. The flat portions 97 are portions that are leftflat without being covered by the rough surface 96.

Since configurations and functions other than those described above arecommon to the baseplates of the first, second and fourth embodiments,like numbers are used to designate common portions of these threeembodiments, and a description of those portions is omitted.

It is to be understood, in carrying out the present invention, that thestructures and arrangements of the constituent elements of thesuspension, including the plate portion, boss portion, protrusions, andreference mounting surface of the baseplate, may be suitably modified.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. A disk drive suspension comprising: a baseplate fixed to a suspensionbearing surface of an actuator arm of a disk drive; and a load beammounted on the baseplate, wherein the baseplate comprises a firstsurface including a reference mounting surface in contact with thesuspension bearing surface of the actuator arm, a second surface locatedopposite from the first surface, a boss portion configured to beinserted into a mounting hole formed in the actuator arm, and aprotrusion formed so as to project outwardly relative to a thickness ofthe baseplate from at least one of the second surface and a part of thefirst surface off the reference mounting surface.
 2. A disk drivesuspension of claim 1, wherein a hole into which the protrusion isinserted is formed in a region of the load beam which overlaps thebaseplate.
 3. A disk drive suspension of claim 1, wherein the protrusionis shaped so as to project in a circular arc from the first or secondsurface along a profile relative to the thickness of the baseplate.
 4. Adisk drive suspension of claim 1, wherein the boss portion is allocatedon the first surface, and the protrusion is allocated on the secondsurface.
 5. A disk drive suspension of claim 1, wherein a hole intowhich the protrusion is inserted and which avoids interfering with theprotrusion is formed in the load beam.
 6. A disk drive suspension ofclaim 4, wherein a hole into which the protrusion is inserted and whichavoids interfering with the protrusion is formed in the load beam.